Induction of Regulatory Dendritic Cells by Lactobacillus paracasei L9 Prevents Allergic Sensitization to Bovine ��-Lactoglobulin in Mice

Abstract

Supplementation with probiotics can protect against the development of food allergies by modulating the host immune response; however, the mechanisms are not fully understood. The objective of this study was to investigate the allergy-reducing effects of regulatory dendritic cells (regDCs) induced by Lactobacillus paracasei L9 (L9) in β-lactoglobulin (BLG)- sensitized mice. The L9 supplement suppressed the aberrant balance of Th1/Th2 responses to BLG in mice, via upregulation of the CD4+CD25+Foxp3+Treg cell responses. The amount of CD4+CD25+Foxp3+Treg cells in mesenteric lymph nodes increased by 51.85%. Furthermore, administration of L9 significantly induced the expression of CD103 and reduced the maturation status of DCs in mesenteric lymph nodes, Peyer's patches, and spleen. Bone marrow-derived dendritic cells (BM-DCs) were activated by L9 in vitro, with an approximate 1.31-fold and 19.57-fold increase in expression of CD103 in CD11c+DCs and the level of IL-10 production, respectively, while the expression of CD86 did not change significantly. These data demonstrate that L9 reduced the BLG allergic sensitization, likely through regDCs mediated active suppression.